We analyzed the records of 26 pregnant patients receiving chronic steroids to assess the combined effect of pregnancy and glucocorticoid administration on glucose tolerance. Five patients (19.2%) developed diabetes mellitus, four of whom required insulin. In a pregnant control group of 1325 patients, 53 patients (4.0%) developed diabetes mellitus, five of whom required insulin. Glucose intolerance was significantly higher in the steroid-treated group (p = 0.003). Comparison with a nonpregnant steroid-treated control group (47 patients, 15% of whom developed diabetes mellitus) showed no significant different (p = 0.23) between the two. All pregnant steroid-treated patients developing diabetes mellitus began steroid therapy after conception, whereas none of the patients receiving steroid therapy before conception developed glucose intolerance (p = 0.012). There does not appear to be an additive effect of steroid treatment and pregnancy on glucose intolerance; however, all patients receiving steroids should undergo periodic glucose screening.